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Want to meet demand for leak detection?

By Lance Anderson, Anderson Manufacturing

Some people wrongly perceive the process of leak detection to be almost mystical. Fortunately, we live in a world governed and ordered by natural laws, not magic.

Most leak detection tests require background knowledge of nothing more complex than simple physics and common sense. A good leak detector will find it valuable to have a basic knowledge of mathematics, hydraulics, mechanics, electronics, and acoustics. Rather than depending exclusively on teachings from “experts” for this understanding, we suggest resting upon your own observation and common sense.

For better understanding, you may want to augment your observational knowledge with a study of basic concepts available in simple text books or on internet websites. If you weren’t paying attention during your high school physics class and need a little refresher, there are many good YouTube videos that make these topics understandable. You’ll probably be amazed at how much more interesting these subjects are when they are actually applied to real-life problems.

One example of how knowledge of basic physics and common sense can be helpful is in the area of pressure testing, where myth and rumor are prevalent.

Most people understand the mechanics of plugging lines and inducing and measuring pressure to watch for a loss. However, there is a great deal of confusion over when and whether to use air or water as the pressure testing medium. To answer these questions for ourselves we find it helpful to consider three “Pressure Testing Principles”: 1. Air escapes from leaks faster than water.

2. In a line containing a mixture of air and water, air will stay high and water will stay low regardless of the pressure.

3. Air compresses under pressure and water does not.

The principles apply to all pressure tests and must be considered in concert (not individually) to properly determine what’s going on. One might think, for instance, that because air escapes from leaks faster than water it would be smart to use air for a test to determine if the line is leaking. However, we must also consider principles #2 and #3. If the line is filled partially with water — and we don’t know where the leak is — just because we are putting air into the line doesn’t mean that air is escaping from the leak.

Leaks at the low part of the plumbing will be losing water even though air is being added to the line. This water escapes from the leak slower than air, and when combined with the fact that compressed air tends to cushion the observation of a pressure drop in the line (meaning that the more air there is trapped in a line, the slower a loss of volume from the line will be observed as a loss in pressure) a leak in the low part of the plumbing may not result in a tell-tale drop in pressure.

Because water does not compress under pressure, a line filled with water will show a quick drop in pressure with the slightest loss in volume out of the line. As a result, the rule of thumb is to use water for the test of a line that is already filled or partially filled with water. A line filled with air (for instance in new construction) could be tested with air because fast flowing air will escape from any leak regardless of its location in the pipe. However, when using air, one must be careful not to raise the pressure above a safe range as plugs that “pop out” under air pressure will be much more dangerous than those that pop out under water pressure because of the expansive force of the air.

These principles also apply when we are trying to pinpoint the location of underground plumbing leaks by making a noise that can be detected with a listening device. In this case, air must reach the leak in order to make a bubbling sound as it escapes into water-saturated soil. Because we know that air fills the top part of the pipe and water fills the bottom, and because we don’t know if the leak is in the low part of the pipe or the high part of the pipe, we will likely have to purge water from the line to be assured that air is reaching the leak.

A common myth is that air and water can be mixed together in a “mixing chamber” of a pressure testing apparatus and that they will stay mixed in the line. This belief is disproved by actual observation. Once in the pipe (and even in the “mixing chamber” itself), the air and water behave according to principle #2 — air at the top and water at the bottom. The truth is that putting both air and water into a line from one location creates noises inside the pipe that can be confused as leak sounds. And if the leak is in the low part of the plumbing, even though this “mixture” is going into the line, air may not be escaping from the leak . . . thus no leak sound.

Sometimes on large leaks or in situations where soil does not stay saturated, it may be necessary to induce both air and water at the same time. If this is necessary, it is much better to put water in from the low end of the plumbing and air in from the high end rather than trying to “mix” them at one location. This method ensures that noises will be made at the leak but not in the lines.

For more information and diagrams on pressure testing and sonic detection, visit the instructional section on pressure testing at our website (

Why is leak detection a great opportunity?

Years of record new pool installations, increasing drought related water restrictions, and a lack of skilled labor have all contributed to a growing demand for swimming pool leak detection services.

In an industry that is all about keeping water in a useable, attractive, functioning enclosure, leaks are pervasive problems that will at some time or another affect every pool. They raise their ugly heads at the wrong times in a whole variety of ways and for a whole host of reasons. They can hide in fittings or cracks in the shell of the pool, behind tiles, anywhere in intricately patterned liners or in the hundreds of feet of underground plumbing snaking around the pool. It’s no wonder that the demanded specialty of leak detection generates premium service rates. But that’s not the only benefit. Being able to find and fix these pervasive problems reinforces your expert status, generates other repair or renovation business, and can be mentally satisfying

How is leak detection different from other types of pool service work?

The leak detector’s product is information. Unlike a pool builder or a repair technician who follows procedural steps to build or repair something, a leak detector gathers and analyzes information in a process that narrows all possibilities down to a specific explanation of what is causing the observed problem. The basic problem-solving process used by a leak detector is similar to the way you might purchase a new service vehicle. First you confirm you really need a new vehicle and why your current solution needs improvement. Next you eliminate certain options — maybe by vehicle type (truck or van)

or maker (Ford or Toyota). Finally, you examine the details within your narrowed set of options. Following a proven mental framework such as this avoids time wasted with “hunting and pecking” for a solution.

What characteristics make a good leak detector?

In a nutshell, leak detectors must be good critical thinkers. Good leak detectors are able to collect, manage, and analyze a large amount of information. They are tenacious puzzle solvers who are adept at logical thinking and enjoy a challenge. In addition to logically processing collected information, they also have to be good at discerning whether the information they collect from their customers and the tests they do at a pool provide information that is helpful and true. This generally requires that they have some basic knowledge on pool system operation and have a good understanding of natural laws related to hydraulics, acoustics, evaporation, and electronics. This knowledge comes in handy as various tests and diagnostic tools are used at various points in the process.

What are the key tools needed for a pool company to start offering leak detection services?

Dye Testing Tools: Includes dye tester syringes, concentrated leak dye, inspection mirrors, and pipe isolating cones.

Pressure Testing Kit: A good pressure testing kit should feature straight-sided test plugs in a variety of sizes and styles to fit various plumbing features. It should also include a pressure tester that allows for the induction of air and water into plumbing lines.

Electronic Listening Device:

These devices use sonic technology to listen for the precise location of plumbing leaks in pressurized lines.

Dive Equipment: SCUBA or compressor operated air source allows for complete structural inspection and repair.

Optional Tools

Hydrophones: Hydrophones can be plugged into electronic listening devices to listen for static leaks underwater.

Electronic Vinyl Liner Leak

Detector (LeakTrac 2400): This device finds leaks by putting a small electrical charge into the pool water, then tracks the flow of electricity as it makes connections to ground through penetrations in the liner.

Rapid Water Loss Sensor (Leakalyzer): This device enables technicians to quickly determine how much water a pool is losing by measuring water level changes down to the 10,000th of an inch and plotting those changes in real time on a digital graph.

Why are these tools important as starter pieces?

While many leaks can be found by using a simple dye testing kit without getting in the water, if you’d like to offer leak detection as a complete service, we recommend investing in a more complete package of equipment that includes a pressure testing kit, electronic listening device, and diving equipment. Depending on what part of the country you are in, the addition of a hydrophone or electronic vinyl liner leak detector will make your work more efficient.

To pinpoint plumbing leaks, you’ll use the pressure testing kit and electronic listening device. The first step is to pressure test plumbing lines with water to determine which lines (if any) are leaking. Even if you don’t find that any lines are leaking, running a pressure test is an important part of a complete leak detection job, because it gives your customers the valuable assurance that their plumbing is sound.

If you find a line that’s losing pressure, you’ll use an electronic listening device to pinpoint the precise location of that leak. Electronic listening devices work by listening for the sound of air escaping from a pressurized pipe into water-saturated soil. When this sound is made correctly, electronic listening devices can pinpoint leaks quickly and accurately from above the deck without having to push or pull anything through the line. Choose a listening device that has advanced frequency filtering capabilities and a well-protected microphone to help zero in on the sound you’re listening for and avoid hearing distracting outside noise.

Dye testing supplies are used for identifying structural leaks in the pool. To dye test successfully, you’ll need a syringe-style dye tester with a thin extension tube or “needle” to allow for the precise placement of dye within a quarter inch of the suspected leak. The best leak dye is specially formulated to hold together well underwater. Because of the precise nature of dye testing, if you’re hoping to confirm the location of anything below the first several feet of the water line, you’ll also need diving equipment that allows you to spend some time in the water.

Hydrophones, which are underwater microphones that attach to your electronic listening device, can be used to quickly identify problem areas while you’re standing on the deck. These tools are particularly helpful on concrete pools where the leaks are usually in defined suspect areas like cracks, fittings, and skimmers. If there is a large enough leak present, you’ll hear the whooshing, jet-engine-like noise of water escaping through that leak when the hydrophone is placed close by. Keep in mind that many small leaks don’t produce enough sound to be audible with a hydrophone. That’s why it’s important to confirm suspect areas with a dye test to make sure that you’re not missing anything before leaving the job.

If you work in an area where vinyl liner pools are common, an electronic vinyl liner leak detector like the LeakTrac 2400 makes quick work of finding even the smallest leaks hiding in the camouflage of today’s patterned liners. The LeakTrac 2400 tracks electrical current as it penetrates the liner, leading you to the precise location of the leak while you stand on the deck. While you may have to get in the pool to do a patch, at least you’re not spending a lot of time in cold water just looking.

Another helpful tool regardless of where you are is a rapid water-loss sensor like the Leakalyzer. This tool graphs precise water level changes in real time — helping you determine how much water a pool is losing to a leak in just 10-15 minutes. The ability to quickly identify and quantify water loss helps leak techs avoid wasted time on pools that aren’t leaking, and call backs by confirming that a pool is no longer losing water after repairs have been made.

What are some tips for getting started?

Make sure the pool is actually leaking before starting your work. There’s no harder leak to find than one that isn’t there! An understanding of evaporation rates — which can vary dramatically from pool to pool and day to day — is important to confirming that observed water loss is really due to a leak. An “Evaporation Estimator,” which uses your local weather data to calculate an estimated evaporation rate for the day you are doing a job, is available at Anderson’s website:

Work systematically through the pool, focusing on specific components one at a time (i.e. skimmers, lights, liner, etc.). As you inspect each component, you should be able to either find a leak or eliminate the component from the search because it is leak-free. Following a systematic process keeps you from wasting time and results in a thorough job. It’s also a good idea to record the results of your inspection as you go so that a report can be delivered to the customer at the end of the job. Anderson Manufacturing Company now offers a subscription-based app called Leak Logic that facilitates this process.

Trust the results of your tests instead of relying too heavily on information provided by the customer or your initial suspicions. If you understand the tests you’re running and perform them correctly, you can be confident in what you find, even if it’s different than what you expected.

What’s the first step to getting started in leak detection?

Sign up to attend a one-day comprehensive training class at Anderson’s facility in St. Paul, MN. Anderson has a comfortable indoor facility that includes both classroom and hands-on laboratory areas so you can learn and practice the skills and principles needed for effective leak detection. Each one-day class covers a tried-and-tested framework for completing jobs efficiently and effectively, a review of the physical principles related to all observational tests performed, and opportunity to use and understand the most advanced diagnostic equipment available. Anderson also offers a large amount of training material at no cost on our website, www. Visit the “training” page under the “Getting Started” menu to access this free information and to see a list of scheduled classes.

Lance Anderson has been helping swimming pool service professionals profit from leak detection for more than 30 years. He is the owner of Anderson Manufacturing Company ( a supplier of specialized equipment, tools, and supplies used for finding and fixing swimming pool leaks.

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